package com.itany.corejava.day03;

public class Test7 {
    public static void main(String[] args) {


        double sum=0.0;

        int f=1;
        for (double i = 1; i <= 20 ; i++) {

            double temp=i+(2.0*i-1)/(i*i)*f;

            sum+=temp;

            f=-f;
        }


        System.out.println("sum = " + sum);


    }
}
